Method of making resilient heel lifts



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ATTORNEY Feb. 23 1926.

- W. J. TOMPKINS METHOD OF MAKING RESILIENT HEEL LIFTS original FiledJune 10 1921 Patented Feb. 23, 1926.

UNITE stares WILLIAM J. TOMPKINS, OF MOUNT VERNON, NEW YORK.

METHOD OF MAKING RESILIENT HEEL LIFTS.

Application filed June 10, 1921, Serial No. 476,421.

To all whom it may concern:

Be it known that I, W'ILLIAM J. Tonin- KINS, a citizen of the UnitedStates, and resident of the city of Mount Vernon, in the county oflVestchester and State of New York, have invented certain new and usefulImprovements in Methods of Making Resilient Heel Lifts, of which thefollowing is a specification. j

This invention relates to resilient heel lifts. In the familiar type offlat rubber heel lift, as distinguished from the concaveconvex type, itis a well known fact that a tight fitting contact of the marginal edgesof the lift, at its attaching surface with the face of the. leatherheel, cannot be maintained and that in a short time the edges of therubber lift will separate from the heel face. In order to overcome thisobjectionable feature of the flat type of heel lift, the concave orconvex lift has been devised. The concavo-convex lift most widelyemployed is provided with concentric attaching and tread surfaces,respectively concave and convex, and of semisplierical curvature, In

other words, this lift may be considered as a section ofa hollowspherical body. It is manifest that when such a lift is flattenedagainst a leather heel to bring its concave surface in contacttherewith, the rubber 1s tensioned and the lift, tending to reassuineits normal shape exerts a very tight frictional pressure at its marginaledges against the heel face. While the objection referred to. is thusobviated in the concave-convex type of lift, the use of such lifts asheretofore constructed also presents certain ob ectionable features.

- One of the most objectionable of such features arises from the factthat it is not possible to completely flatten a spherical surface. Thus,when the concave surface of this lift is applied to the leather heelface and pressure exerted against the convex tread surface, a constantlyincreasing conipressing action takes place on the convex s de of thelift, while a corresponding expansive action takes place on the concaveside of the lift. The lateral expansion of the lift at the face of theheel is strongly resisted by the constantly increasing tension andfrictional pressure of the marginal edges of the lift against theleather heel. Therefore, the rubber stock of which the lift is formed iscrowded inwardly so that the entire area t' e s me? witnesses s t was fte Renewed August 1, 1924.

contact with the rubber heel, but is spaced therefrom, at differentpoints, particularly between the fastening nails, which results in acorresponding proturberance or projection on the tread surface of thelift. Therefore, it is clear that when this type of lift is flattenedand nailed or otherwise attached to the shoe heel, it will not have aflat or level tread face, all parts of which are located in a singlehorizontal plane. On the contrary, there will be produced an uneventread surface so that the wearer experiences a sensation of insecurity.This type of heel also has another, more or less, serious objection inthat the inward crowding pressure of the stock exerts an uneven lateralpressure against the fastening nails, which causes the nails to becomeloose. This is particularly evident in those cases where the rubber liftis applied to a shoe heel made of paper or other composition material,in which the nails do not hold as in leather. Heels of this constructionare quite common in the cheaper grades of shoes.

It is, therefore, the primary object and purpose of the presentinvention to provide a method of producing a heel lift of the corncavoconvex type in which the objections above noted are not present,which objections to a certain degree have been responsible for therather limited use of this type of heel. In one embodiment of theinvention I provide a heel lift made of rubber or other resilientmaterial, the lift having a concave attaching surface, not necessarilysemispherical, and a convex tread surface which is more or lesseccentric to the concave surface, the lifthaving its smallest thicknessat the central portion thereof and gradually increasing in thickness tothe marginal edges. It will be at once seen that with a heel lift ofthis construction, when pressure is applied to the convex surface andthe lift is flattened against the shoe heel and nailed or otherwiseattached thereto, the rubber stock will crowd inwardly from the marginaledges of the lift, as in the old type of concavo-convex lift, but thisinward crowding of the stock will merely equalize the thickness of thelift througl'lout its area and compensate for the thinness of the stockin the normal condition of the lift so that a depression or cavity willnot form in the tread surface of the lift, but this tread surface willbe absolutely level and flat and have a l Parts there f di eased Withina horizontal plane, coinciding with the perimeter of the tread surfaceof they marginal edges of the lift.

In obtaining this improved result I have evolved a method ofascertaining the particular degree of eccentricity of the tread surfacewith respect to the attaching surface of the lift, in accordance withwhich the molds are made for the production of the improved lift.

lVith the above and other objects in view, the invention consists in themethod of malting heel lifts, as will be hereinafter more fullydescribed, illustrated in the accompanying drawings and finallyincorporated in the subjoined claims.

In the drawing wherein I have illustrated several desirable embodimentsof the in-' vention, and in which similar reference characters designatecorresponding parts throughout the several views,

Figure 1 is a perspective view of one form of the improved lift in itsnormal condition proved lift.

applied and nailed thereto.

Referring in detail to the drawing and more particularly to Figures 1, 2and 3 thereof, I have illustrated a lift of rubber or other resilientmaterial having a concave attaching face substantially semispherical inshape. It is, however, not essential that this attaching face or surfaceshall be of seinispherioal shape, since other shapes may be provided,the important consideration being that there shall be a sufiicientconcavity to produce a tight hugging action of the entire marginal edgeportion of the lift against the leather heel when the lift is In thedrawing, the numeral 9 indicates generally a heel lift of this typehaving a convex tread face 10, and a concave attaching face or surface11. v

It will be noted from an examination of Figures 2 and 3, that the treadsurface 10 is'not concentric with the concave attaching surface 11, buteccentric thereto. Thus. the central portion of the lift as shown at 12,is relativelythin and the lift gradually increases in thiclrne ssfrom'this central portion to IGS, breast edge 18, and to its rear end a"magi-arena antenna, Likewise,

the lift gradualy increases in tliickncszs transversely thereof, fromthe central portion indicated at 12 in Figure 3 to the sic e marginaledges. It is to be understood from this description that at the rear endof the lift, the thickness indicated between the lower and upper edgesof the lift 15 and LT respectively, is substantially the same as thethickness of the lift between-its lower and upper edges 16 and 18respectively at the breast 13. Likewise, in Figure 3 of the drawing, thethickness at one side of the lift between the upper and lower edges 20and 21 is substantially the same as the thickness between the lower andupper edges 22 and 23 at the opposite side of the lift. It will thus beunderstood that the lift uniformly increases in thickness in oppositedirections from its central portion outwardly to its marginal edges bothlongitudinally and transversely of the lift.

In Figure 4 of the drawing 1 have shown the lift 9 applied to theleather heel 25 of the shoe 26 by means of the nails 27 or otherequivalent fastening means. ll hen pressure is applied against theconvex tread surface f the lift to flatten the same against the leatherheel, as seen in Figure 4, it is appar cut that the gradually increasingfrictional pressure of the marginal portions of the liftagainstthe heelface exerts a resisting influence against the lateral expansion of thelift, at its concave face, so that the rubber stock crowds inwardlytowards the relatively thin central portion of the lift. Therefore, anyhollow; or depressure in the tread face of the lift which mightotherwise form is compensated for, so that when the lift is finallyflattened and attached to the heel, the tread surface thereof isabsolutely flat and level with all portions disposed in a commonhorizontal plane, coinciding with the perimeter of the tread surface.

In Figure l, I have indicated by means of the-dotted lines l0protuberances or projections which are produced upon the tread surfaceof the lift in the old ype of lift where the concave and convex surfacesconcentric with each other. It will be noted that these projections ofthe tread surface occur particularly between the fastening nails and atthese points, also the concave surface opposed to the heel face isspaced. from the leather heel. This is caused by the inward crowding ofthe stock, the outward expansion of which is resisted by the greattensional pressure of the marginal portions of the lift against theheel.

In Figure 5 I have illustrated a slightly different embodiment of theinvention, wherein the lift is provided'with a relatively shallowconcave attaching surface 11 and a tread surface 10 which consists of aplural ity of singularly related an 1- plane surfaces. Whedtl is liftisappliedto the leather heel and the lift flattened to bring the concavesurface 11 into contact throughout its area with the heel face, thetread surface l0 is disposed slightly beyond or inwardly of a horizontalplane, coinciding with the perimeter of said tread surface.

In other words, in this case, as in the preferred embodiment of theinvention, no part of the read surface projects beyond the horizontalplane referred to, so that in neither case will the lift, when attached,present an uneven tread. In this last de scribed form of the invention,the same tight hugging action of the marginal edges of the lift againstthe face of the leather heel is secured, while all portions of the liftare located between true parallel horizontal planes, which respectivelycoincide with the perimeters of the attaching and tread surfaces.

In practice I have found that the necessary degree of eccentricity ofthe tread surface of the lift with respect to the attaching surface maybe accurately ascertained for the purpose of producing the molds wherebythe lifts are manufactured, by attaehing an old concave-convex lifthaving concentric attaching and tread surfaces to a heel or other fixedpart, as indicated in Figure 6, and then cutting off or planing downthat portion of the tread surface of the lift which protrudes beyond thehorizontal plane, coinciding with the perimeter of the tread surface atthe margin of the lift. lhis protruding part, which is cut from thelift, 1 have indicated at 10 inFigure 6. hen the lift is removed fromthe heel, it

. will then he found that the lift is relatively thin at its centralportion and the tread surface is eccentric to the attaching surface,substantially as indicated in Figures 2 and 3. From the model thusproduced templets are made in accurate conformity to the cur vature ofthe concave and convex surfaces,

drawing, the form and construction of the improved heel lift and themanner of producing the same will be clearly understood. By means of theimproved construction an absolutely level or flat tread surface isobtained when the lift is attached, and the objections to the oldconcave-convex type of heel lift are wholly eliminated. While theprojections or protuberances on the tread surface of the heel lift ofthe old type are primarily due to the cause above referred to, theseprotuberances are accentuated by. the

. fastening nails exerting a compressing action on the stock and tendingto pull the tread surface down. It is somewhat difficult to accuratelyindicate this uneven appcarance of the tread surface in the drawing, butit is quite evident in the use of the old type of lift. It will also beunderstood that in Figures 2 and 3 the illustration of the cocentricrelation of the convex tread surface to the concave attaching surface ofthe lift is more or less exaggerated. In the actual lift, the degree ofeccentricity very slight. However, it is sufficient to insure the engagment of the concave attaching surface throughout its area with theleather heel when the lift is flattened and to compensate for the forcesof compression and expansion acting to crowd the rubber inwardly fromthe margin toward the central portion of the lift.

As above stated, the particular shape of the concave attaching face ofthe lift is immaterial, and my present improvement may be carried out orproduced in connection with many different types of concavoconvex heellifts known in the art. It is, therefore, to be understood that I do notdesire to be limited to the specific forms herein illustrated, butreserve the privilege of adopting all such legitimate changes as maybefairly embodied in the spirit and scope of the appended claims.

I claim:

1. A method of manufacturing resilient heel lifts which consist in firstflattening a concavoconvex resilient lift having concentric attachingand tread surfaces, then removing from the tread surface of theflattened lift all stock protruding beyond a horizontal plane coincidingwith the perimeter of the tread surface, then detaching the lift andmaking mold dies in accordance with the curvatures of the concave andconvex surfaces of the modified lift and then producing resilient liftsby means of the mold dies, having convex surfaces conforming to thecorresponding surfaces of the modified lift.

2. In a method of manufacturing resilient heel lifts the steps whichconsist in first flattening a ooncavo-convex resilient lift havingconcentric attaching and tread surfaces, then removing from the treadsurface of the flattened lift all stock protruding beyond a horizontalplane coinciding with the perimeter of the tread surface, and makingmold dies in accordance with the curvatures of the concave and convexsurfaces of the modified lift.

In testimony that I. claim the foregoing as my invention, I have signedmy name hereunder.

lVILLIAllf J. TO J'IPKINS.

